In the US alone, several million surgical procedures are performed each year that involve the removal of tissue, or a portion of an organ, because of some pathology involving this tissue, particularly those involving benign and malignant tumors. Although a significant percentage of these tissues and organs are removed with conventional surgery, a major effort has recently been made to utilize laparoscopic and other minimally invasive techniques that have reduced morbidity. However, performing this surgery through laparoscopes requires significant training and advanced skills of the attending physician. Perhaps the most severe challenge of laparoscopic surgery is in the control of bleeding. It is the purpose of this research effort to design, construct, and test a device that would permit these surgical procedures, particularly those involving a partial nephrectomy, to be performed without fear of blood loss. We have developed a technique, using high intensity ultrasound, that enables the clinician or other skilled operator to perform laparoscopic tissue ablation with minimal bleeding. The apparatus involves the use of high intensity ultrasound, radiated from two line sources of transducers that are attached to a laparoscopic instrument that can be inserted though a conventional trocar into the body. The method involves the use of the high intensity ultrasound to induce a plane of cauterization through the tissue, proximal to the region of interest, including the occlusion of blood vessels, thus isolating this region from its vascular supply. Consequently, the organ containing the region of interest, once transected, will not bleed. This minimally invasive technique has the promise of greatly expanding the use of laparoscopic procedures, permitting, for example the widespread practice of performing partial nephrectomies, thus preserving a large number of kidneys, organs that are in major demand for transplant surgeries. The specific aims of this effort are as follows: (1)To design, construct, and acoustically characterize an improved HIFU clamp that will achieve completely transmural ablation in a porcine kidney model; (2) To perform a series of experiments in tissue phantoms and ex vivo tissues to test the effectiveness of our engineering prototype; (3) To perform a series of acute experiments in a porcine animal model, both with the HIFU Clamp as well as the Nussbaum Clamp; and (4) To perform a series of survival experiments in a porcine animal model with the HIFU clamp deployed laparoscopically. The successful completion of the major goals of this effort provides the basic technology that would lead to increased use of laparoscopic procedures during organ and tissue sparing surgeries.